Chemosensory signals received during mating activate brain regions along the vomeronasal and main olfactory pathways. These activated regions contain cell bodies and fibers of gonadotropin-releasing hormone (GnRH) neurons. Chemosensory input can be detected by vomeronasal organ (VNO) and/or main olfactory system, but mating in sexually-na[unreadable]ve male hamsters is impaired by vomeronasal organ removal (VNX) and not olfactory lesions. Intracerebroventricular (icv)-GnRH can restore mating behavior in na[unreadable]ve VNX males and may facilitate transfer of olfactory information to the medial amygdala, a critical relay for the chemosensory input driving mating behavior, in na[unreadable]ve intact and VNX males. Initial experiments suggest that the effect of icv-GnRH on Fos expression following electrical stimulation of the main olfactory bulb (MOB) is different than its effect on Fos expression following conspecific chemosensory stimulation. These and other data suggest that GnRH may affect medial amygdala responses to socially relevant and socially non-relevant stimuli differently. This application will investigate its modulation GnRH of medial amygdala responses to stimulation of chemosensory pathways relevant for behavior.